Various kinds of wireless communication systems, such as a wireless LAN and Bluetooth (registered trademark), are widely used.
Those wireless communication systems each have an advantage and a disadvantage.
Hence, it is popular to use plural wireless communication systems in combination, not to use one wireless communication system alone.
However, there is a difference in the frequency bands used by the individual wireless communication systems.
Accordingly, in order to use plural wireless systems, it is necessary to transmit/receive wireless signals in respective multiple frequency bands. In order to transmit/receive wireless signals with multiple frequencies, it is necessary either to use plural antennas each for a single frequency or to use a multi-frequency antenna coping with multiple frequencies. However, it is advantageous in terms of miniaturization, simplification and cost reduction of an antenna to use the multi-frequency antenna than to use the plural antennas each for a single frequency.
An illustrative multi-frequency antenna is disclosed in patent literature 1. This multi-frequency antenna comprises a conductor plate, a dielectric body provided on the conductor plate, and plural antenna elements contacting the dielectric body and having different characteristics from one another. The plural antenna elements operate at different frequency bands from one another. Consequently, a single antenna can operate at multiple frequency bands.